10 December 1976,
Five prisoners disappeared from Basauri prison. They all thought they had fled and the Spanish police launched a huge search operation. However, these prisoners remained hidden on the roof or in the loft for 52 days, preparing for the final escape. They were prisoners. Patxi Arana and José Ignacio Aramayo of ETA; social prisoners of PCE Pedro Martínez Ilarduya and José Vicente Daroca and Santiago Marcos Tolsa.
Source:
Patxi Arana, Journal of an attempted escape. (Ddt Books).